BT60 Hawkeye upscale

I finished this up over the holidays:


I always liked the Estes Hawkeye, but was always afraid I'd loose it. Mine was (is) painted bright red and only has one or two flights on it. Twenty years ago, I built a 2X upscale, but decided now that a BT60-based 3X was necessary. At this size, though, the turbine bodies on top of the wings looked silly empty, and the whole rocket was begging for more detail. So I built cores for the turbines to give them a more realistic look. Primary mount is 24mm, but the two turbine cores are built to accept 13mm engines. According to RockSim, a pair of A3-4T engines would boost it an additional 125 feet or so. The main wings are 1/8th ply, the canards and rudder fins are 1/8th balsa. I added cardstock strips to the rudders to help stiffen them some and to add some detail to the surface. Decals came from Excelsior, but most of the panel lines and such are drawn on by hand. Paint was done using Duplicolor's Metalcast system, smoke over the silver basecoat. I call it "cosmic countershading". It has a 24" ripstop parachute. Since its the middle of winter, I'm waiting till fair weather to fly it. Unfortunately, the local club doesn't fly again till the end of May...

:y: That's too pretty to fly. Sorry.
I love the way you built the turbines. That's a very cool detail. One that I'd never have thought of in this lifetime.

That looks amazing... love it!

KUTGW! OL JR

Thanks!

One question I have about this model is with regards to the clustering. In this specific case, the extra motors are really just there for show - a pair of 13mm motors don't really add that much overall. They would simply burn out and pop themselves out the rear. But while they are burning, since the mounts are offset from the rocket's centerline, would the offset thrust cause it to veer in a negative pitch direction? Or is the thrust so minimal compared to, say, an E12 engine, and the fins so large that it would be negligible? It didn't seem to make a difference in the RockSim model, but I'm not sure if that's really accounting for the offset correctly. I didn't really design this to be a cluster model per se, it only occurred to me that the turbine cores could be built to accomodate 13mm motors when I started making them. So flying on a single 24mm is easy enough, but it would look pretty cool to have the turbines thrusting as well...

Yeah, that COULD be a serious problem... (off-axis thrust). It's POSSIBLE the fins could overcome it, but it would take some careful simulation to make sure. If you're talking about adding the small motors to THIS rocket, my experienced guess is that indeed it would cause the rocket to loop or severely arc in the direction opposite the motor offset. Now, I said "THIS rocket" for a reason... if the build was designed with the motor tubes in the outboards CANTED to align with the CG of the rocket, then I think it would probably work okay, since all the motors would be thrusting through the vehicle's CG. As it is, thrusting linearly with the long axis of the rocket, and being offset (and having their thrust lines offset) from the CG, it's going to produce a torque force on the vehicle under flight for as long as the outboard motors are thrusting proportional to the thrust force and the arm of inertia between the thrust force centerline and the vehicle CG (if that makes sense).

There's a couple alternatives here if you're really set on having the outboards have motors in THIS (as built) rocket... one I can discuss here in the open forum... The alternative would be to use a motor with an "insignificant" amount of thrust for the outboards... IE Micromaxx motors... They thrust for less than a second, and are essentially 1/8A motors... so you *might* be okay with those motors... plus they weigh less than the other motors you mentioned, which will keep the CG further forward and thus increase the CG/CP static stability relationship. The off-center thrust may still cause the rocket to arc SOME off the rod/rail, but it should be minimal and once the thrust phase of the MicroMaxx motors ceases, the offset torque force should stop as well, causing the rest of the flight to be straight from that point on...

I'll PM you with the other suggestion...

Later! OL JR

Well, if nothing else, I was originally planning on capping off the turbine core tubes with BT5 Bomarc engine cones, which would still look suitable. I have the parts, I might use them for display regardless...

OK, over the weekend, I filled/sanded/painted a pair of BT5 Bomarc engine nose cones to closeout the turbine cores. So even if I don't sort out whether or not I use mini engines in them, I at least can finish off the opening.

That is truly stunning build quality.